Along with miniaturization of semiconductor elements in recent years, manufacturing apparatuses as well as detection apparatuses or evaluation apparatuses are required to achieve high-precision according to the miniaturization. For example, in order to evaluate whether shape and size of patterns formed on semiconductor wafers are correct, Scanning Electron Microscope with length measurement function (hereinafter, referred to as length measurement SEM) is used for that purpose. Length measurement SEM is one of charged particle apparatuses that irradiate electrons onto a sample to measure the length of the sample.
When evaluating samples using length measurement SEM, positioning precision of the sample stage has a significant effect on measurement precision such as resolution or pattern dimension. Specifically, even when the sample stage is not moving at a predetermined position for sample observation, nanometer-scale vibration of the stage may degrade image quality of the observed image.
Patent Literature 1 listed below uses an ultrasound motor using two piezoelectric actuators diagonally extending with respect to the moving direction of the stage. Patent Literature 1 achieves both of normal quick movement and nanometer-scale movement by providing a phase difference between applied voltages of the two piezoelectric actuators.
Patent Literature 2 listed below controls, using two active brakes with symmetrical shapes, applied voltages of a piezoelectric actuator that drives a brake, thereby suppressing position offsets of the stage due to the contact between the brake pad and the stage.